Data from the 2002 Supermarket Panel are used to estimate a supermarket production function with weekly gross margin as the output measure and store selling area and total labor hours as variable inputs. The model also includes productivity shifters describing format and service offerings, store ownership structure, unionization, and adoption of new information technologies and related business practices. The null hypothesis of constant returns to scale cannot be rejected. Increases in ownership-group size, warehouse and supercenter formats, unionization of the workforce, and adoption of vendor-managed inventory and a frequent-shopper program are all associated with significantly higher productivity.